Impreza Trans Warning: Grinding and Slipping Issues

I had a very similar transmission fault on my 2018 Subaru Legacy last year. I have some experience working on cars but transmission issues are complex, so I took it to a workshop. The symptoms matched yours exactly, transmission warning light, limp mode, and rough shifting. Initially thought it was a transmission sensor problem, but the diagnostic revealed the transmission oil level was critically low. This triggered the pressure switch safety system. The fix involved: Full transmission oil level check, Replacing contaminated transmission fluid, Cleaning the transmission sensor, Running diagnostic tests Total cost was 365€ for parts and labor. The transmission has worked flawlessly since then. Important: Low oil levels can seriously damage transmissions. The grinding sounds you mention are concerning and could indicate internal wear. To help diagnose your specific case, could you share: current mileage, When was the last transmission service, Does the grinding noise happen in specific gears, any previous transmission repairs These details would help determine if your issue is similar or potentially more serious.

The grinding noise occurs mainly when shifting from 1st to 2nd gear. My current mileage is 7797 KM and the last service was just 2 months ago. The transmission fluid was checked then and everything appeared normal. During service, they connected a pressure gauge and found no irregularities with the transmission pressure. The transmission oil sensor readings were also within specs at that time. After hearing about your experience, I am wondering if a follow-up check of the transmission fluid level might be worthwhile, even though it was recently serviced.

As mentioned in my previous reply about my Legacy, transmission issues can be tricky to diagnose. The grinding specifically between 1st and 2nd gear is quite different from what I experienced, especially given your recent service and low mileage. Since your transmission oil level was verified during the recent service and the pressure readings were normal, I would now lean more toward a potential transmission sensor fault rather than a fluid issue. When my transmission sensor was cleaned during service, the technician mentioned these sensors can sometimes give false readings even with correct oil levels. The fact that your symptoms appeared shortly after a complete service where everything checked out makes me suspect either: A faulty pressure switch sending incorrect signals, An intermittent transmission sensor issue, A wiring problem affecting sensor readings Given the low mileage and recent service, I would recommend having the transmission sensor and related wiring thoroughly checked. My repair showed that even small sensor faults can trigger similar symptoms. The diagnostic for this specific check typically costs around 100€, much less than a full transmission repair. Would you be able to note if the grinding noise changes intensity with engine temperature? This detail helped diagnose my sensor issue.

Thanks for those details about the transmission sensor diagnosis and your experience with the grinding noise. Since my problem started, I have noticed the grinding is actually more pronounced when the engine is cold, especially during the first few minutes of driving. It does seem to improve slightly as everything warms up. The service center just called back and said they can check the transmission sensor and wiring tomorrow. They quoted 95€ for a full diagnostic including checking all transmission related sensors. Given the symptoms and everyone's feedback about sensor faults, this seems like a good next step before considering more extensive transmission repairs. I will have them verify the transmission oil level again as a precaution, even though it was checked recently. Better to rule out any fluid issues completely. Will update once I know more about what they find with the sensor testing.